


i'm on your side and that's forever

by artistical_failure



Category: Rise of the Teenage Mutant Ninja Turtles (Cartoon 2018), Teenage Mutant Ninja Turtles - All Media Types
Genre: Donnie is a good Big Bro, Protective Donatello (TMNT), and Little Bro, even if he says he'd sell them to satan for an ice cream cone ('AND I'M LACTOSE INTOLERANT'), he tries not to show it but he really does love his brothers
Language: English
Status: Completed
Published: 2020-06-18
Updated: 2020-08-05
Packaged: 2021-03-03 20:34:56
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 3
Words: 2,609
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24781657
Author URL: https://archiveofourown.org/users/artistical_failure/pseuds/artistical_failure
Summary: Donnie looks out for his family in ways they don't always realize.
Comments: 26
Kudos: 206





	1. Chapter 1

**Author's Note:**

> THIS IS BASED OFF OF @kal-zoni's ART ON TUMBLR (https://jesuisfabulous.tumblr.com/post/616350879002640384)
> 
> Okkk so! Before I get started, I just want to say that I'm only a beginning writer, so if this seems a bit slow or fast paced or choppy or whatever... I'm very sorry, I don't have a lot of practice. I've written stories before but they have been PROMPTLY abandoned because I get one single burst of motivation every two years or so and then it disappears in a week. So. Hopefully that won't happen with this story! I'll probably only keep this to 4 or 5 chapters so I don't run out of inspiration (or motivation) like halfway through.

He is seven years old and Mikey wants papa to read a book.

Donnie is secretly thrilled, because it’s a juvenile book, sure, but Mikey is only five and it’s a book nonetheless. Besides, that’s how his own love of reading developed, so it’s a start. He kind of hopes Mikey will be a nerd like him. Maybe then he’ll finally have someone to talk to about his passion for literature. 

“Papa!” Mikey exclaims, all bright-eyed and cheery in a way only five year olds can be. “I found a book about you!”

He holds it up to show their father, who has yet to spare him a glance. The glossy cover, with the words ‘Papa Goes To The Market’ scrawled across the page, reflects the harsh neon light of the TV. 

“Papa!”

Only a grunt.

Donnie, watching from one of the many corridors in their dwelling, narrows his eyes.

The book is pushed forward again, more insistent this time. “Read please!” 

It works, in a way. Their father addresses him with a huff, obviously annoyed: “Orange, can’t you see I’m watching quality television over here?” He casts a glance at the child. “I don’t have time for…”

Donnie decides to make his presence known. He takes a single step forward -- not much, but he’s mostly out of the shadows now, and he may only be seven but he’s a looming figure when half-bathed in darkness. The movement catches Splinter’s attention and his eyes dart over to Donnie. 

Donnie fixes him with a dead stare. 

_ Tell him no, _ the stare says. _ I fucking  _ dare  _ you. _

Splinter’s eyes widen. He shoots a quick glance at the TV -- probably imagining all the horrific science channels he’d have to watch if Donnie decided to mess with it again as punishment. He turns back to Mikey, debating.

Donnie takes another step.

“Of course, my little mandarin!” Splinter exclaims, voice an octave higher than usual as he reaches over the armrest to pick Mikey up. “I’ve got all the time in the world!”

Mikey giggles. Splinter takes the book from his hand and starts reading aloud, sweat pouring down his face. “Here we go… ‘One lovely Saturday morning, papa woke up and got out of bed…’”

“Papa! That’s you!”

“Well, it’s not actually -- um, I mean, yes! You’re right, my child, it is me.”

Donnie observes the scene for a few more moments. Satisfied, he sinks back into the shadows, the sound of Splinter's voice fading as he heads back to his room.

(Years later, Mikey develops an interest in art and focuses his efforts on painting and drawing. Still, he keeps the story tucked away on an oak bookshelf and recalls with a grin the day Splinter had read to him.

"Dad never really did that stuff, so it stands out," Mikey says, when Leo asks why he still has it on display. "It's just a nice memory, y'know?"

Donnie keeps scrolling through his phone without comment, but the corners of his lips twitch up behind the screen.)


	2. Chapter 2

**Notes for the Chapter:**

> INSPIRED BY/BASED ON @kal-zoni's ART ON TUMBLR (https://kal-zoni.tumblr.com/post/178790836797/was-meant-to-post-this-about-a-week-ago-but-whoop)
> 
> OKAY I've decided I wanted to make this a 3 chapter fic; one chapter for Mikey, one for Raph and one for Leo. I might add more later but I think setting a small goal like this for myself will make me more likely to achieve it lol
> 
> anyway, enjoy!!

He is ten years old when Raph insists on carrying the first aid kit to the park.

  


“I’m the oldest so I should be the one to bring the important stuff,” he announces, patting the fanny pack that Leo had given him for his birthday (ironically, but Raph loved it) with a certain amount of pride. Donnie squints and wants to point out that being older doesn’t necessarily equate to being responsible --  _ look at dad _ , he wants to say -- but he bites his tongue and instead slips some medical supplies inside his own bag.

  


Just in case.

  


The four of them set off to the park close to their home in the sewers, Mikey clinging to Leo’s neck with childish glee. This is the first time in months that they’ve been allowed to visit what Donnie has deemed ‘the outside world’ and their excitement is palpable. It took Leo half an hour of flattery and Donnie promising to upgrade their cable for Splinter to let them out, and even then he was very strict with only allowing them to wander around for two hours after the sun went down.

  


(“If any humans discover you, they will want to find you,” the rat had grumbled, clicking through the channels on TV. “And fighting them off will interrupt my television time.”

  


Leo had shot Donnie a quizzical look and Donnie only shrugged. He was letting them go, wasn't he? What else could they ask for?)

  


They rush to get there, Donnie rattling off directions from a map of the city he found in one of the tunnels, and arrive minutes after they’d taken off. Leo is the first to rush onto the empty playground and Mikey shrieks in delight as the blue-masked turtle sprints toward the swings.

  


Raph grins and focuses his attention on the slides.

  


Reluctantly, Donnie heads over to the abandoned seesaw.

  


In all honesty, he’d rather be using this time to collect scraps at the junkyard. He has projects to work on. Besides, there’s nothing to do when the humans aren’t around -- observing people is much more fun than playing on plastic, shoddily-built inanimate obstacles.

  


_ And cleaner _, he thinks in disgust, moving his hand away from a yellow stain that smells alarmingly of sweat and urine. At the least the stuff in the junkyard is useful and mostly uncovered in bodily fluids. But the junkyard is far and he hasn't memorized the way there yet -- the map is safely tucked away in his room -- so he sits for a few minutes, bored out of his mind, wondering if he could manage to sneak away to look for some spare parts without the others noticing. 

  


“Hey, Donnie!” Leo grins, suddenly appearing before him. He plops himself down on the other end of the seesaw and Donnie’s seat rises from the counterweight. “Wanna play together?”

  


Not particularly, and Donnie tells him so.

  


Leo only laughs. “You’re such a wet towel, Donald. Lighten up!”

  


“ _ Donnie _ . And it’s ‘wet blanket’, not ‘wet towel’.” A thought occurs to him suddenly and he twists in his seat. “Wait. Aren’t you supposed to be watching Mikey?”

  


A resounding ‘SMACK’ rings through the yard, followed by the familiar sound of Mikey’s wailing. Donnie leaps from the seesaw.

  


“Uh,” Leo says, as Donnie turns on him.

  


“You left him ALONE on the swings?!”

  


“I forgot?” Leo offers meekly.

  


Any hope of scavenging for parts is quashed. Donnie clenches his jaw and reminds himself that murdering his brother is still very much illegal and, even if human laws are technically not applicable to mutants, their dad would most likely be upset at losing a son.

  


_ No matter how bone-headed he may be. _

  


“Come on,” he snarls, grabbing Leo’s upper arm and dragging him across the yard. Leo looks very much like he wants to protest but thinks twice when the lampposts surrounding the park illuminate Donnie’s murderous expression. He's silent as they make their way over to the swing set.

  


Raph is already there, helping a sniffling Mikey sit up.  He looks up as the twins approach, fixing his gaze on Leo. 

  


“You were supposed to watch him,” he says, careful to keep any accusation out of his voice.

  


Leo huffs and crosses his arms. “I forgot, okay?  _ Sorry _ , jeez.”

  


Raph frowns.  Mikey sniffles again.

  


After a moment of tense silence Leo deflates, uncrossing his arms. “Donnie looked lonely,” he mutters, kicking at some loose gravel. “I thought he maybe wanted someone to…" he trails off, hunches his shoulders. "Whatever. It doesn’t matter.” 

  


Raph’s expression softens. Donnie sighs and releases Leo’s arm from his hold, pushing away the residual frustration bubbling in his chest.

  


“Thanks,” Donnie says. He hefts his backpack. “But. Next time, just… focus on Michael, okay? I’ll be fine.”

  


Leo responds with a small, embarrassed smile. He kneels down next to Raph, who stands back, and takes Mikey from his arms. “Hey, Mikey… sorry I left you like that.” 

  


Mikey pouts and points to his knee. “Hurts,” he mumbles, clinging to Leo’s arm. 

  


Leo winces at the scrape on their baby brother’s knee. “Um…” He turns sheepishly to the other two. “Did anyone bring bandages?”

  


Raph’s face brightens. “No worries! I came prepared,” he declares, at the same time that Donnie reaches for his backpack, saying, “Yeah, I should have some…”

  


He looks up when their older brother goes silent. Raph’s expression is crestfallen.

  


Donnie makes a split-second decision.

  


“...Now that I think about it,” he says in a monotone voice, dropping the hand that was reaching for the bag, “I left them back at home…”

  


Raph straightens up, suddenly hopeful. Leo gives him a look that can only be described as bewildered. 

  


“Rats,” Donnie adds in a tone completely deadpan.  You know, for emphasis.

  


He feels kind of dumb but at least Raph’s face is lighting up again, overjoyed at the chance to step up and be the responsible one. “Well lucky for you!” Raph exclaims, rummaging through his fanny pack, “‘cause I--”

  


He cuts himself off. His expression falls again.

  


“Shoot,” he mutters, staring down into the empty pack. “I forgot them too…”

  


_ Crud _ . If he thinks they don’t have any bandages they’ll have to return home to get them -- and that’ll cut into the brief outside playtime they have.

  


Donnie knows where this will inevitably lead, and he’s not having any of it. Before Raph can berate himself and start spiralling into a pit of depression and self-esteem issues, Donnie reaches into his backpack and inconspicuously drops the first aid kit at Raph’s feet.

  


Raph looks down at the ‘thud’. “Oh hey!” he exclaims, bending down to pick it up. “Never mind, I just dropped them!”

  


He hands them to Leo, who takes them with a sigh of relief. “Thanks, Raph, you’re a lifesaver.”

  


“What would we do without our big brother looking out for us?” Donnie drawls, offering a reassuring smile as he pats Raph’s arm.

  


Raph beams.

  


Once Leo finishes fixing Mikey up they clamber back on the swings, this time with Leo never leaving Mikey’s side. Raph returns to the slides and Donnie watches from the seesaw. The two hours are over surprisingly soon and as they trek back to the sewers, Leo turns his attention to Donnie.

  


“Man, I can’t believe  _ you  _ forgot the first aid kit,” his twin laughs. He pokes Donnie’s side. “Getting soft in your old age, there, Don? Get it? ‘Soft’, ‘cause you’re a soft-shell--”

  


“You’re not as clever as you think you are, Leon.”

  


Leo sticks his tongue out, like every mature individual does. 

  


They squabble for a bit, with Leo pestering him and Donnie issuing a litany of threats if he doesn’t shut up. It’s annoying, but Raph is grinning the whole way back, so he thinks it was worth it.

  


Leo takes a break from pestering Donnie and mentions how lucky it was that Raph brought the band aids along. “At least we can always rely on our big bro,” he says, giving their brother a friendly nudge. Mikey, from where he’s seated on Leo’s shoulders, coos in agreement. Raph flushes with pride.

  


Donnie smiles and ducks his head.

  


Yeah, he thinks. Definitely worth it. 


	3. Chapter 3

**Notes for the Chapter:**

> WHOOPS SORRY THIS TOOK SO LONG
> 
> This is the first time in a while that I've had access to a computer and, consequently, google docs, which is where i work on my drafts (I tried downloading it on my phone but that wouldn't work for some reason?? Technology kinda sucks ass). anyway, here's the last chapter of this installment, with leo! i hope you guys enjoy :>
> 
> based on this comic (https://kal-zoni.tumblr.com/post/181043406147/headcanon-leo-has-insomnia-but-since-hes-always ) by @kal-zoni on tumblr!

He is fourteen years old when he and April take down the Purple Dragons.

He shuffles into the common area at 3 am, completely exhausted -- this evening’s adventures have mostly taken a physical toll on him but there’s a lingering ache in his chest that has nothing to do with the hits he’d taken. He really loved that jacket, dammit. 

It’s gone now, though, and April had patted his back sympathetically, offered a “That’s rough, buddy” and suggested he spend the rest of the night at her place.

“We can get takeout, if you want,” she’d said. “I know a few places that are open. Besides, my parents are out of town for the week, so we can watch Jupiter Jim without worrying about them crashing the party.”

Which would’ve been nice any other time, but he was just tired and wanted to pass out in his own bed. April shrugged, gave him one last shoulder squeeze and then departed with a flippant “see you tomorrow, Don”. So he stumbles into the living room after a long trek home, drained physically and emotionally, and he’s planning to head straight to his room and pass out for about a week when a voice pulls him off course.

“Look who’s back,” the familiar, grating voice of his twin sing-songs. Leo’s watching him from the couch, cup of tea in hand, fully decked out in his blue striped pyjamas and nightcap. He has the TV on but nothing is playing -- the DVD symbol drifts aimlessly from corner to corner. “And no satin jacket, I see?”

“Oh, put a sock in it, Leo,” he growls, dragging himself into his room. “It’s too late in the night to deal with you…”

He’s taken exactly one step over the threshold before his mind catches up with him. Donnie peers around the corner as a thought suddenly occurs to him.

“Wait, what are you still doing up so late?”

“Just chillin’,” Leo drawls, swirling the mug of tea absentmindedly, eyes locked on the harsh neon screen.  _ Nothing is playing, _ Donnie notes again.

He frowns and checks his phone. “Well, you’ve been ‘chillin’ for about five hours now… Aren’t you tired?”

His brother shrugs. “Can’t sleep.”

“Seriously?” Donnie asks, incredulous. He gestures to Leo’s getup. “But you look so snuggled up.”

Leo laughs and leans forward. “I know, right?”

It sounds almost manic. Donnie tilts his head, reappraising his brother. Leo’s eyes are wide but the bags underneath them are prominent, even in the dark. His foot is tapping rhythmically against the floor -- what was that called again? Right, stimming. A way to relieve heightened emotions, most likely frustration. 

Donnie remembers years ago, when they were both younger and blissfully unaware of the dangers lurking outside their cozy home in the sewers, how Leo could never just  _ be _ . He remembers the late nights where Leo couldn’t seem to stop moving, energy coursing through his veins even after a day of sprinting through the tunnels. He remembers waking up in the middle of those nights to the sounds of Leo’s sobbing, muffled against their father’s robes as he asked through hiccups and sniffles why he couldn’t just  _ stop _ . Why he couldn’t be normal, and what was  _ wrong _ with him?

He remembers how their father never had an answer, and how he would only hold Leo tighter as the tears started up again. 

Donnie casts a glance at his bed, laying a few feet away. He’s so  _ tired,  _ and it looks so comfortable and inviting.

He looks back to Leo, seemingly staring right through the screen.

He weighs his options, then makes a decision. 

“Well,” he sighs, forcing his legs toward the couch, “I’ve had a pretty crazy night, so I’m high on adrenaline… wanna binge some Jupiter Jim?”

Leo looks taken aback, but only for a second. A grin quickly replaces the surprised expression. “Yeah, that sounds pretty good.”

“Cool.” Donnie plops himself down next to his brother and snatches up the remote. “We’ll watch 70s-80s.”

His twin nods, then shoots him a suspicious glance. “None with Atomic Lass though… you get really weird with those ones.”

“Tch. Uncultured swine.”

  
  
  


(The next morning, Raph heads into the common room to find the two of them snoring away on the couch in a mess of entangled limbs. He smiles, shakes his head and heads into the kitchen to get started on breakfast.

But only after taking a couple hundred photos. _Blackmail, baby_.)

**Notes for the Chapter:**

> that’s a wrap!! thanks for sticking with me thru this guys ^~^ all your comments & kudos are greatly appreciated!


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